Fogging is a phenomenon which occurs due to water droplets condensed on the surface of an object when a surface temperature of the object is around a dew point. Here, when an angle between a condensed water droplet and a surface of an object is large, a globular water droplet is formed. Light is scattered at water droplets formed in this way and thus a surface of an object is visually clouded.
Since transparency of solar cells, displays, glasses, and vehicle glasses is decreased due to such fogging, optical devices do not exhibit normal characteristics when fogging occurs. In particular, in the case of vehicles, fogging is often generated on a surface of a front glass due to a difference between an interior temperature and an exterior temperature, which disturbs a driver's view and, accordingly, may decrease driver safety.
As technology to prevent fogging, a technology of manufacturing an ultra-hydrophilic surface by forming minute structures on a surface has been used. Since the ultra-hydrophilic surface has a contact angle of 10° or less to water, water droplets are not formed on the ultra-hydrophilic surface and spread rapidly, whereby light is not scattered. However, such a surface has a disadvantage that the structures are too minute and thus it is difficult to maintain the shapes thereof when pressure and abrasion from the outside are applied thereto. Therefore, the structures cannot be applied to products, such as vehicles and exterior glass of buildings, requiring high durability.
Recently, research into technologies of preventing fogging by forming a coating film using epoxy resin exhibiting water absorption on a surface of a product is actively underway.
Korean Patent No. 10-1322577 discloses an anti-fogging article having a crosslinked resin layer that includes a polyepoxide-based substance and a hardener. However, this disclosure has a limitation wherein a saturated water absorption amount is not high and thus anti-fogging performance cannot be continuously maintained.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.